Heat a large nonstick skillet (or one that has been sprayed with cooking spray) with a tight-fitting lid, over medium heat. When hot, add the butter and onion. Sauté, stirring often, for 3 minutes, or until the onion starts to become translucent. Add the ginger and garlic and stir-fry for 1 minute. Add the turmeric, curry powder, chile powder, and Garam Masala and continue to stir-fry for another 30 seconds.

Add the tomato and potato to stir-fry for 1 minute more, then pour in the water and bring to a boil. Cover and simmer until the potato is barely done- just tender not mushy- 8-10 minutes, lifting the lid and stirring occasionally.

Add the spinach, cover and cook for 1 minute more, or until spinach wilts, and season with tamari, salt and pepper. Add the tofu.

Either stir the cooked soba into the vegetable mixture, or use the vegetable mixture as a sauce for the soba.